Air intake systems for motor vehicles may include an air intake tract in which an air filter housing or other housing (for example, an acoustic resonance chamber, air plenum, etc) is arranged. Air filters are used to provide a necessary source of particulate free filtered air for safe operation of an internal combustion engine. Various types of noise silencers or resonance chambers may also be applied in the air intake tract of an engine to achieve attenuation of undesired engine operating noises transmitted in the intake tract.
During the cylinder air intake cycle of the engine, a vacuum pulse is generated in the air intake tract by the opening and closing of the cylinder air intake valves. These pulsations may result in undesired noises radiating from the intake tract. Other noises on the air intake tract may be generated by the engine vibrating the air intake system. Some of these noises or noise frequencies may be undesirable. These undesired engine sounds may be channeled back through the air intake tract from the engine. Undesired sounds may also be generated by the intake air flowing through a restriction or other geometry that introduces turbulence into the flow. The generation of turbulence consumes energy from the airflow stream and may result in an increased restriction to airflow in the air intake tract.
An air intake tract may include an air filtration system in which an air filter element, such as a pleated panel filter element, is enclosed in an air cavity within an air filtration housing and divides the cavity into a clean side and a dirty side. The air filtration housing may include an air inlet and air outlet port or connection in communication with opposing sides of the air cavity and filter element.
Often the air filtration element has a larger surface area than the cross sectional area of either the inlet or outlet ports on the filter housing providing a more tortuous than desired airflow pattern in the housing and resulting in the generation of airflow turbulence within the air filter housing. The positioning and/or alignment of the air inlet and/or outlet ports on the housing may further contribute to this tortuous airflow path and generation of undesired airflow recirculation patterns or turbulence. These flow recirculation patterns consume a portion of the kinetic energy from the airflow stream resulting in increased resistance to airflow.
The air intake tract may be provided with a noise suppression device such as one or more acoustic resonators. For example, U.S. Pat. No. 7,198,017 discloses an acoustic resonator chamber provided on the air intake tract and configured to attenuate certain undesired noises.
U.S. Pat. No. 7,150,260 discloses an air filter housing disposed in an air intake tract that in at least one embodiment may include one or more resonance chambers integrated into the air filter housing.
U.S. Pat. No. 6,792,907 discloses a variable Helmholtz resonator disposed on the air intake tract of a motor vehicle. The resonator is dynamically adjustable to cancel selected frequencies of a time-varying acoustic sound signal.
While these devices are useful in reducing transmitted noise in engine air intake tracts, none of the solutions address the problem of improving the airflow path in an air intake tract to minimize pressure loss and integration of acoustic countermeasure control technology into the airflow guidance solution.
Therefore, there remains a need in the art for an air intake system that incorporates air guide features operative to invisibly guide the airflow along a low-loss path, thereby reducing airflow turbulence and airflow resistance or pressure drop. There is a further need to configure these countermeasures to additionally serve as tuned acoustic countermeasures within the air intake tract to optimize utilization of available under hood space and reduce material cost.